Tuesday, January 29, 2008

LIGO announced earlier this month that they did not detect gravitational wave signals from what was the most expected source of a recent intense gamma ray burst. Scientists theorized that the burst came from the collision of two neutron stars or two black holes, but now that LIGO has ruled that possibility out, they believe it must have come either from a magnetar in the Andromeda galaxy, or something behind the spiral arm of that galaxy. Even though LIGO didn’t detect gravitational waves, that information still gives astrophysicists a lot to work with. This is also an important step for the large detector because this data could not have been found with any other available methods.The Laser Interferometer Gravitational-wave Observatory (LIGO) is searching for gravitational waves, which are most likely created by violent and/or massive events in the universe. Einstein predicted the existence of gravitational waves when he determined that time and space make up a single fabric. His idea of gravity can be analogous to bowling balls on a trampoline. When objects (mainly planets and stars) rest on the fabric of space time, their mass causes the fabric to dip and bend. The more massive the object (heavier the bowling ball), the deeper it sinks on the fabric. This was Einstein’s idea of gravity. So continuing with the idea of a trampoline, massive gravitational events, like the collision of two black holes, are believed to cause ripples in the space-time fabric. These ripples are gravitational waves. If two colliding objects were responsible for an intense gamma ray burst, they would also emit gravitational waves. [As a side note, this analogy is inherently flawed because a bowling ball on a trampoline is under the influence of gravity, so the analogy contains itself.]

Gamma rays are perhaps the most energetic kind of light in the universe. In just seconds, hard gamma rays can emit more energy than the sun will emit in 10 billion years. It can thus safely be guessed that an event causing such a huge energy release will also create gravitational waves. You may have seen a chart of the electromagnetic spectrum, which displays all the spectrum of light that we know of.When light behaves as a wave, it always travels at the same speed, but has different frequencies. This translates into larger amounts of energy. Radio waves have the least energy and the lowest frequency, and gamma waves have the highest energy and highest frequency. Visible waves are somewhere in between. There are “hard” gamma rays of particularly high energy, and “soft” gamma rays, which are less intense.

Gamma ray bursts are also mysterious. While astronomers have multiple theories on where gamma ray bursts can come from, the results from LIGO show that our methods of discerning them are somewhat limited. This particular burst was observed on an eye-line with a spiral arm of the Andromeda galaxy, but it could have come from within the galaxy, or beyond it. By merely observing the light waves from that direction, (whether you use visible, infrared, x-ray or gamma), scientists are limited by the fact that it is difficult to determine how far away a light source is. LIGO offers a different method for observing astronomical events, thus opening a whole new window of observation. Gamma ray bursts will most likely pair with events that LIGO will focus on, so the two should assist each other for years to come.

Magnetars, which I mentioned earlier, are a key source of the most intense gamma rays. Read this article from Scientific American for an absolutely breathtaking story about magnetars and the most intense gamma ray bursts in the universe.

An update on LIGO events are usually released about once a month, either through CalTech or MIT. A recent article by Kathy Svitil explains the science of LIGO very well. At the moment, LIGO is anticipating the start of work on Advanced LIGO, an addition to the current project that will make it 10 times more sensitive. LIGO representatives expect that gravitational waves will most likely not be detected before completion of Advanced LIGO, sometime around 2010.Image Credits:http://www.ego-gw.it/virgodescription/pag_1.htmlhttp://www.phys.ufl.edu/~reitze/teaching/spring2006/phy3101.htmhttp://einstein.phys.uwm.edu/PartialS3Results/node2.htmlhttp://saturn.jpl.nasa.gov/mission/nav-uplink.cfm

Thursday, January 24, 2008

Normally I try to not get too political on this blog, because I’m pretty sure the FBI is monitoring it (I also try not to be too sarcastic, but sometimes it’s called for). This blog is a representative of the American Physical Society, which has a strong and respectable political image to uphold. But even the president of the American Physical Society Arthur Bienenstock had no qualms about waving his figurative fist at Congress and the White House for cutting nearly a billion dollars in science funding from the FY08 budget. Earlier this month he sent out an email to all APS members expressing his frustration at the budget cuts, and urging members to write to Congress and ask for supplemental science funding. It is with this in mind that I write this entry with both freedom and restraint.The budget cut was simply a blind-sided attack on science, especially after the strong declarations made by the America Competes Act. National agencies had already planned to continue with at least the same funding as last year, if not more. The sudden shockwave of decreased funding forced them to not only cease work on new projects, but stop current projects before their scheduled finish dates. This includes abrupt and unexpected cut backs on projects that impact national issues like climate change, alternative fuels, and cyber security. Not to mention jobs.Cutting out a billion dollars from science funding the same year Congress and the White House declare that America needs to get more competitive with rising international science and education programs, is what I’d call a lack of understanding. I’d also call it a slap in the face, a kick in the groin, and absurd. It’s like handing a starving man a can of peanuts, only to have two fake snakes jump out of it. The joke is lost, and it’s just mean.The America Competes Act at its best is a strong initiative that promotes science and science education in America; the project aims to give every child in America the best science education we can, and to reward risk and innovation in science research. At its worst, it seems nationalistic. The proposals are stuck somewhere between setting a new bar of quality (despite where other countries are at), and a childish desire to keep America numero uno in every event on the playground. And apparently members of the administration have watched one too many inspirational football movies, and need only a motivational speech to win the big game. Scientists, on the other hand, need teachers, labs, and salaries.Primarily, what kind of message are we sending to the children we’re trying to teach math and science to if we won’t even fund jobs in those areas?These cuts also bring up the interesting debate about where we’d like to see our national funds go. Speaking as a scientist, if the government wanted to cut money from science funding to ensure that every child in America had *good* health insurance, or that every person in the world who asked for it could have access to clean water, I’d be all for it. In an ideal moral setting, purely humanitarian efforts should come before science, but also before art, and music, and nuclear arms. But the world’s a bit more complicated, and purely humanitarian efforts don’t really exist. So in this imperfect world, it’s important to realize that science is one of the primary reasons why our country is in a position to make humanitarian efforts. It’s one of the main reasons why health care is getting better and more accessible every year. Science fuels countless aspects of our economy from countless angles. Economic competitiveness, technological advancement, and our overall national mindset are all significantly impacted by the state of science in our nation. And besides the iPods and top-notch PhD programs, science is one of the last active proponents of logic, and for that reason alone we must save it.----------------------The Department of Energy, the National Science Foundation, and the National Institute of Standards and Technology have all been allotted less money than in FY07, as opposed to promised increases. Damage to these organizations will also result in cuts to university proposals. The American group working on the International Linear Collider was given only a quarter of what it expected. Because America’s contribution to the ILC project is so large, and because Britain also pulled out their funding this year, it’s unknown what the fate of the entire project will be. SLAC was forced to suddenly cut 125 jobs, with more on the way, and it looks like FermiLab is in a similar situation. While this affects the entire scientific community, high energy physics seems to have been hit the hardest.This week Arthur Bienenstock sent out another email, thanking those 3,000 members for writing to congress, and encouraging other members to do so (this was still a very low percentage, out of 46,000 APS members). In addition, the DOE and NIST released reports describing the impact of the budget cuts. It was pretty consistently negative.

Tuesday, January 22, 2008

Hello regular readers and accidental tourists. Apologies for the sparse posts these past few weeks. We're busy getting a few things ready for the APS March Meeting in New Orleans, which although is still over a month away is moving in on us quickly. Mostly we're sorting through the 6,000 abstracts and hundreds of invited talks that will be presented at the 5 day conference and picking out our favorites. In doing so, I've found some really cool stuff, all of which I'd love to share with you. Today's post is just something to tide you over until I can put together something fancy.Take a gander at the website of David Hu, a physicist at the NYU Courant Institute. Hu specializes in analyzing biological systems with physics. For instance, at the March Meeting, he'll be presenting his work that questions how snakes move the way they do - particulary in their unidirectional slinky-like motion. At times, he gets down to the nitty-gritty of analyzing the very details of motion. He and his team created a crawler model to follow the snake's motion. They'll also be presenting results about certain snake behaviors that result in their tying themselves into knots.In previous years, Hu and his team have done extensive work on bugs that walk on water, examining how they manage to not break the surface tension and stay on top, and how they propel themselves along so gently. For this work they also built a robotic mimic: the Robostrider!Here I've included some of my favorite pictures from the site, but I encourage you to click the link and see the presentation Hu and his team give.Enjoy!

Wednesday, January 16, 2008

Astronomers are celebrating the beginning of Solar Cycle 24: the beautiful beginning of the switch of the sun’s magnetic polarity that creates a tangle of magnetic field lines around the sun, and wreaks havoc on cell phones, power grids, GPS and ATM’s.

Satellite based technology may see some severe consequences around 2011 if this turns out to be an intense solar cycle.In addition, scientists really have no way of preventing the problems that the sun’s magnetic field could cause.The cycle could cause major problems for GPS systems, and in cases where extreme accuracy from those systems is crucial, we may just have to wait it out.

Astronomers identified the beginning of the sun cycle because of the appearance of a very special sunspot.Sunspots, which are fairly common, are like bottle caps over areas of intense magnetic fields.When the field gets all built up, it bursts out of the surface through the sun spot.Scientists are able to determine the polarity of each sunspot, and when a sunspot appears with the reverse polarity of its buddies, we know the new sun cycle has begun.

Scientists are still split on just how bad this particular cycle will be.Like the seasons, the solar cycles occur in a regular pattern: lasting, on average, 11.1 years, with a possible range of 2-3 years.But their severity is debatable.Scientists have been observing solar cycles for hundreds of years, but we have only been monitoring their intensity of since the 1970’s, so they still haven’t been able to observe much in the way of different trends from cycle to cycle.

When the sun begins a new cycle that means its magnetic field is switching polarity.Changing polarity is nothing more than changing the plus side of a magnet to a minus side, like switching the side that attract metal and the side that repels it.Magnets exist because of because of the same phenomena as electricity (hence, ELECTROMAGNETISM!), so there is literally a switch in the direction that electrons flow.

The magnetic fields of the Earth and the sun are created by magnetic charges running through the core of the spheres: like a long, rectangular magnet put through the middle of a bowling ball.The sun’s magnetic field, during low cycle periods, is about as powerful as a refrigerator magnet, which is 100 times as strong as the Earth’s.Still, that’s a pretty big magnet.During the peak of the solar cycle, the entire magnet actually becomes much stronger than it is during the normal season.

Magnetic field lines from the sun can severely damage a planet, as they have done to Mercury, which is now lacking much of an atmosphere.But Earth is protected by its own magnetic field.During the peak of solar cycles, the change in polarity of the sun’s magnetic field can lead to a jumble of magnetic field lines, and solar winds can carry the effects of the magnetic field far out into the solar system.

Image: The magnetosphere shields the surface of the Earth from the charged particles of the solar wind. It is compressed on the day (Sun) side due to the force of the arriving particles, and extended on the night side. (Image not to scale.)

It’s been theorized by a few scientists that the Earth’s magnetic field changes as well, but over much, much longer periods of time; somewhere on the scale of tens of thousands to millions of years.

Wednesday, January 09, 2008

I love to report any kind of media featuring a physics or astrophysics theme, even if the creators steer off course from the real science. This first one deserves a post all it's own. Amazing stuff.

The Music of Space

Sun Rings—The Kronos Quartet and composer Terry Riley have constructed a performance joining a string quartet with recorded space sounds that include deep-space lightening, crackling solar winds, jovian chorus, and others. In addition, the performances feature visual creations by Willie Williams. Music in nature isn't a new idea, but this adds quite a mysterious twist to it. It's actually been going on since 2004, so I'm a bit slow on the up-take.

University of Iowa professor Don Gurnett has collected space sounds for over 40 years. Here’s a sample of one of the sounds he recorded.

I’ll just let these songs speak for themselves (although the second one is instrumental). For purely musical reasons, these are two of my favorite songs of the year. The science themes are icing on the cake:

The film Sunshine had it's US premier in July, but it didn’t get a very good welcoming in the US, so many of you may not have heard about it. I’ll let you be the judge of the film itself, which you can at least guess will be well-crafted with director Danny Boyle at the helm (Trainspotting, 28 Days Later). The film doesn’t really hold on to the physics ideas it starts out with, and ends up being more like the emotional rollercoaster ride that Event Horizon was. Still...icing on the cake.

The film theorizes that our sun could suddenly be subject to sudden death if a rogue Q-Ball hit it. A Q-Ball is a type of soliton, which is a type of wave that doesn’t change, meaning it maintains its shape indefinitely. A regular soliton can remain unchanged because the forces that would normally change its shape and the forces that would normally reduce its amplitude exactly cancel each other. A Q-Ball has this stability due to a conserved charge. Those are rough descriptions, but the best descriptions are fairly mathematical. There are soliton waves in the ocean that travel for thousands of miles without changing shape or size. It’s a rare event because of how exact the circumstances have to be. Because waves need a medium to move in, like water or air, you can’t just have a soliton running around in space. Some physicists think dark matter is made up of some type of Q-Ball, in which case they might be made up of anti-matter. For that reason they wouldn’t interact with planets, but the fusion process inside a star could cause interaction. It’s also theorized that Q-Balls arise in supersymmetric fields, suggesting they formed at the beginning of the universe and have just been floating around since (this is the idea Sunshine took, and I'm not sure why that allows the Q-Ball to affect stars, but it’s not really mentioned in the film).

Enjoy the trailer (warning, it's not for kiddies), and check out the Sunshine website’s own discussion of the science of the film.

Send any other physics-in-media suggestions you have! Especially ones most people won't have heard about. It’s sooooo cool to be nerdy.

Tuesday, January 08, 2008

I remember when Nickelodeon went through its materials phase and came out with Gak, Floam, Smud, Squand and Gooze; a joyous variety of moldable materials that brought mayhem to carpet everywhere.These substances probably inspired more than a few young sculptors and materials physicists.Here are a some great new developments in materials physics that actually serve a purpose beyond entertaining 12-year-olds.

Metal Rubber

Earlier this year, physicists created something called metal rubber which is pretty much exactly what it sounds like.Watch his video to see what I mean:

Metal Foam

Scientists have created metal foam made of a nickel-manganese-gallium alloy; metal foam is enough to wrap your mind around, but this is pretty much a super material.It’s cheaper, lighter, and potentially stronger than other materials that have its most defining property: it can return to its original shape after being deformed by physical or magnetic force. This is the very first foam with magnetic shape memory.(Photo:http://www.dunand.northwestern.edu/. Scanning electron micrograph of a Vit106 foam.)

Because it’s a metal, scientists can manipulate its shape using magnetic fields, or just the traditional method of smashing it. Scientists hope the foam can be used in tiny motion control devices, space born applications, or in mechanical devices without mechanical parts.Kind of like the ghost in the machine, don’t you think?

By turning on a magnetic field the foam will change shape.Once the field is turned off, the metal maintains its new shape.To get it to start reforming to it’s original shape, simply rotate it 90 degrees.If you’re not familiar with the properties of a magnetic field, this seems like an odd thing to do to make a metal foam start reforming itself to its original shape.But imagine turning a magnet 90 degrees with respect to its poles: you’ll have one end that attracts metal suddenly replaced by the end that repels it.Those 90 degrees reverse the direction of the polarity and cause the foam to reshape itself.

The researchers created the new material by pouring molten alloy into a piece of porous sodium aluminate salt. Once the material cooled, they leached out the salt with acid, leaving behind large voids, hence the foam structure.

Friday, January 04, 2008

The difference between the warm bed and the cold floor in the morning; the painful reminder of the hot stove or the icy metal pole; or even the part of the world we choose to live in; it all comes down to these things we call hot and cold. Yet few of us outside the physical sciences really know what these…things (?)…are. Seriously ask yourself if you know whether or not hot and cold are the same phenomena, or two separate effects. How easy would it be for you to figure out how a refrigerator works; and why do you plug it in if electricity tend to make things hot? And once you’ve mastered those concepts: how do you reach the coldest temperature possible?

NOVA is airing a two part special called “Absolute Zero: The Story of the Harnessing of Cold and the Race to Reach the Lowest Temperature Possible.” The two, one hour specials explore the mysterious realm of the coldest of cold. Part one starts at the turn of the 16th century and explores the first pursuits of scientists to understand hot and cold; the second half follows things up to the present day as scientists look for ways to get within fractions of a degree from absolute zero. Catch it on PBS Tuesday, January 8 and 15 at 8pm EST.

I highly recommend checking out NOVA’s website for some great articles in relation to the special (http://www.pbs.org/wgbh/nova/). Did you know refrigeration is one of the three inventions that most impacted the formation of cities? The three essentials were elevators (allowing for tall buildings = lots of people in small spaces), the telegraph [and later the telephone](allowing manufacturers and businesses to be away from their consumers and/or their producers), and refrigeration (so you didn’t have to have a farm nearby). The article points out that the locomotive often gets the most credit for settling the west, but refrigeration was a comparable development.

My favorite of the articles addresses the burning question: if there is an absolute zero (the coldest possible temperature) is there an absolute hot? Is there a limit to the hottest temperature in the universe? Some say such a temperature is 25 degrees of magnitude hotter than the core of the sun…while others think such an improbable number proves there’s no such thing in nature. There seems to be no solid answer, yet the possibilities are fascinating, and have created quite a stir in physics, astrophysics and cosmology. (This photo shows the sun in ultraviolet light, giving a cool tint to the red hot sphere).Picture Credit: http://www.mudsugar.com/uploads/a_christmas_story.jpg